Gas blast circuit breaker



May 18, 1948. G. BRUHLMANN GAS BLAST CIRCUIT BREAKER Filed Feb. 19, 1944 atented May 18 1948 UNITED STATES PATENT OFFICE GAS BLAST CIRCUIT BREAKER Gottfried Briihlmann, Baden, Switzerland, as-

signor to Aktiengesellschaft Brown, Boveri & Cie., Baden, Switzerland 3Claims. 1

. protective resistance, which assists the extinction of the rupturing arc and prevents the rapid rise of the recovery voltage, is connected in parallel with the switch contacts by means of a spark gap. It has, however, been found that such switching devices can fail to operate when under certain circumstances difiiculties are encountered as regards the extinction of the are at the spark gap which connects up the resistanc or if over-voltages are caused by this arc. The object of the present invention is therefore to overcome these difliculties.

In orderto facilitate the extinction of the are at the spark gap and to enable an over-voltage protection to be obtained with gas-blast circuit breakers having a resistance which is connected in parallel with the switch contacts by a spark gap, at least one additional spark gap is provided which switches a second resistance, whereby in accordance with the invention the resistance switched by this additional spark gap is connected in parallel with the spark gap which connects the resistance in parallel with the switch contacts.

constructional examples of the invention are illustrated diagrammatically in the accompanying drawings where Fig. 1 is a fragmentary longitudinal section through a gas-blast circuit breaker with a hollow contact, all elements which are not essential for an understanding of the invention having been omitted from the drawings; Figs. 2 and 3 are fragmentary longitudinal sections showing alternative arrangements in which the auxiliary electrodes provide a spark gap extending transversely to the direction of the gas blast; Fig. 4 is a fragmentary longitudinal section of a circuit breaker in which the auxiliary electrodes provide a plurality of spark gaps in parallel; and Fig. 5 is a diagrammatic top plan view of the same.

In all constructional examples the hollow contact a is assumed to be stationary and together with the movable pin contact 1) forms a point of interruption where the opening arc, after the nozzle opening has been uncovered by the moving contact, is subjected to a gas blast in the longitudinal direction and thus rapidly deionized. Part of the are thus passes to the electrodes c1, 02 of the spark gap which connects the protective between the circuit breaker contacts a and b. This introduction of a parallel resistance path facilitates the extinction of the arc by preventing a rapid rise of the recovery voltage during the resistance (11 in parallel with the initial arc path Application February 19, 1944, Serial No. 523,111

In Switzerland January 18, 1943 Section 1, Public Law 690, August 8, 1946 Patent expires January 18, 1963 (01. zoo- 148) gap 01, c2, and 02, C3, can form a common element of both.

. Resistance (12 of the additional spark gap can also be employed with gas-blast circuit breakers having contacts moved in opposite directions by the pressure gas as well as with such circuit breakers where both contacts are of the hollow type. The arrangement according to the invention can furthermore be applied to gas-blast circuit breakers with an insulating nozzle inside which contacts are located, and to such circuit breakers where the arc burns transversely to the gas blast.

The number of spark gaps can be increased as desired, whereby the resistances of the even and odd number spark gaps can each be arranged in a series of their own.

Instead of arranging the electrodes of the resistance-switching spark gaps one behind the other in the direction of the gas blast, it is also possible to locate them next to each other transversely to the direction of the gas blast, as shown in Figs. 2 to 4. The resistances switched by the spark gaps c1, 02 and C11, (312 respectively can then be connected either both to the same contact b or each to one of the contacts a, b. The hollow contact a can also be used as an electrode of the spark gap. It is also conceivable that an electrode (:1 lying approximately in the centre of the gas blast can be connected over a resistance (11 with one of the switch contacts I), further electrodes C2-Cs connected to resistances dzds being grouped around the electrode 01 as shown in Figs. 4 and 5.

I claim:

1. In a gas blast circuit breaker, a hollow contact, a contact movable to engage said hollow contact, a first electrode spaced from said hollow contact in a direction away from said movable contact and located substantially centrally in the path of the blast of the are drawn between said contacts, circuit means including a resistance interconnecting said first electrode and one of said contacts, whereby the are drawn between the contacts is shifted to the gap between said first electrode and the other of said contacts, at least one additional electrode spaced from said first electrode and located in the path of the arc blast, and circuit means including a resistance interconnecting said additional electrode and the said other contact whereby the arc is shifted to the gap between said first and additional electrodes.

2. In a gas blast circuit breaker, a pair of relatively movable circuit breaker contacts, passage means for the flow of pressure gas to blast the are drawn between said contacts upon their separation, a first electrode located substantially centrally in the gas blast path beyond said contacts, circuit means including a resistance connecting said electrode to one of said contacts, at least one additional electrode arranged centrally in the gas blast path beyond said first electrode, and circuit means including a resistance connecting said additional electrode and the other of said contacts.

3. In a gas blast circuit breaker, a pair of relatively movable circuit breaker contacts, passage means for the flow of pressure gas to blast the are drawn between the contacts upon their separation, an electrode located beyond said contacts along the axis of the gas blast path, circuit means including a resistance connecting said electrode to one of said contacts, a plurality of additional electrodes arranged about the axis or the gas blast path to define a plurality of gaps with respect to said axially located electrode, and circuit means including resistances individual to each additional electrode connecting said. additional electrodes with the other of said contacts.

GO'ITFRIED BRUHLMANN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 20,044 Clerc July 28, 1936 1,967,989 Clerc July 24, 1934 2,290,004 Thommen July 14, 1942 

